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 A228523 Numbers that are not the product of two Fibonacci numbers (not necessarily distinct). 1
 7, 11, 12, 14, 17, 18, 19, 20, 22, 23, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 41, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 56, 57, 58, 59, 60, 61, 62, 66, 67, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 90, 91, 92 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS All primes except prime Fibonacci numbers are in this sequence. LINKS EXAMPLE Although 12 can be expressed as a product of Fibonacci numbers, it takes three of them, not two, hence 12 is in the list. There is no way to express 14 as a product of Fibonacci numbers since its larger prime factor, 7, is not a Fibonacci number, hence 14 is in the list. 16 is not in the list because it can be expressed as 2 * 8. MATHEMATICA nn = 12; f = Fibonacci[Range[2, nn]]; f2 = Select[Union[Flatten[Outer[Times, f, f]]], # <= f[[-1]] &]; Complement[Range[f[[-1]]], f2] (* T. D. Noe, Sep 03 2013 *) CROSSREFS Cf. A049997 (complement). Sequence in context: A243885 A171017 A195608 * A193301 A213250 A226689 Adjacent sequences:  A228520 A228521 A228522 * A228524 A228525 A228526 KEYWORD nonn,easy AUTHOR Alonso del Arte, Sep 02 2013 STATUS approved

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Last modified May 23 18:08 EDT 2022. Contains 353993 sequences. (Running on oeis4.)